Re: Adaptect raid performance with FreeBSD

From: Ari Suutari (ari_at_suutari.iki.fi)
Date: 01/14/04

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    To: Raymond Wiker <Raymond.Wiker@fast.no>, freebsd-stable@freebsd.org
Date: Wed, 14 Jan 2004 15:11:30 +0200

    On Wednesday 14 January 2004 15:02, Raymond Wiker wrote:
    > Ari Suutari writes:
    > > dd if=/dev/rda1s1a of=/dev/null bs=1m count=100
    > > 100+0 records in
    > > 100+0 records out
    > > 104857600 bytes transferred in 4.193832 secs (25002814 bytes/sec)
    > >
    > > So, I get only about 25MB/s. Shouldn't I be getting something
    > > like 70 MB/s, or even more since there are two disks that
    > > can server read requests ?
    >
    > Have you tried other block sizes? I think you may be able to
    > get better results by going to a lower block size (e.g, 64k instead of
    > 1m). Some experimentation will show which block size(s) work best.

            I tried with 32k, 64k, 256k and 512k. Speed is about the same
            with every block size. Block sizes less than 32k seem to give
            even worse performance.

                    Ari S. 

    -- 
Ari Suutari
Lemi, Finland
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